Background: Population-based estimates of asthma and allergic rhinitis in sub-Saharan African adults are lacking. We assessed the prevalence and determinants of asthma and allergic rhinitis in urban adult Cameroonians.

Methods: A community-based survey was conducted from December 2013 to April 2014 among adults aged 19 years and above (N = 2,304, 57.3% women), selected through multilevel stratified random sampling across all districts of Yaounde (Capital city). Internationally validated questionnaires were used to investigate the presence of allergic diseases. Logistic regressions were employed to investigate the determinants of allergic conditions.

Results: Prevalence rates were 2.7% (95% CI: 2.1-3.4) for asthma-ever, 6.9% (5.9-7.9) for lifetime wheezing, 2.9% (92.2-3.6) for current wheezing and 11.4% (10.1-12.7) for self-reported lifetime allergic rhinitis; while 240 (10.4%) participants reported current symptoms of allergic rhinitis, and 125 (5.4%) had allergic rhino-conjunctivitis. The prevalence of current asthma medication use and self-reported asthma attack was 0.8 (0.4-1.2) and 1 (0.6-1.4) respectively. Multivariable adjusted determinants of current wheezing were signs of atopic eczema [2.91 (1.09-7.74)] and signs of allergic rhinitis [3.24 (1.83-5.71)]. Age group 31-40 years [0.27(0.09-0.78), p = 0.016] was an independent protective factor for wheezing. Determinants of current rhinitis symptoms were active smoking [2.20 (1.37-3.54), p<0.001], signs of atopic eczema [2.84 (1.48-5.46)] and current wheezing [3.02 (1.70-5.39)].

Conclusion: Prevalence rates for asthma and allergic rhinitis among adults in this population were at the lower tails of those reported in other regions of the world. Beside the classical interrelation between allergic diseases found in this study, active smoking was an independent determinant of allergic rhinitis symptoms. Nationwide surveys are needed to investigate regional variations.

pone.0123099.g001: Prevalence of current wheezing by age group and gender.

Mentions:
In univariable analysis, current wheezing was less frequent in the age group 31–40 years relative to other age groups. The prevalence of current wheezing by sex and age groups is shown in Fig 1. Current wheezing was higher in women aged 50 years and above, relative to their male counterparts (p = 0.128). Current wheezing was found in 7.5% of participants with rhinitis and in 2.3% of those without rhinitis (p<0.001). The prevalence of current rhinitis was 27.3% among subjects with current wheezing and 9.9% in those without current wheezing (p<0.001). Six teen (25.4%) participants with asthma ever had current rhinitis and 10% of participants without asthma ever had current rhinitis (p<0.001). Likewise, the prevalence of wheezing was higher in participants with signs of eczema compared to those without (9.4% vs. 2.7%, p<0.001). Allergic rhinitis was more frequent in participants with university education, in smokers and participants with wheezing or symptoms of atopic eczema (Table 4).

pone.0123099.g001: Prevalence of current wheezing by age group and gender.

Mentions:
In univariable analysis, current wheezing was less frequent in the age group 31–40 years relative to other age groups. The prevalence of current wheezing by sex and age groups is shown in Fig 1. Current wheezing was higher in women aged 50 years and above, relative to their male counterparts (p = 0.128). Current wheezing was found in 7.5% of participants with rhinitis and in 2.3% of those without rhinitis (p<0.001). The prevalence of current rhinitis was 27.3% among subjects with current wheezing and 9.9% in those without current wheezing (p<0.001). Six teen (25.4%) participants with asthma ever had current rhinitis and 10% of participants without asthma ever had current rhinitis (p<0.001). Likewise, the prevalence of wheezing was higher in participants with signs of eczema compared to those without (9.4% vs. 2.7%, p<0.001). Allergic rhinitis was more frequent in participants with university education, in smokers and participants with wheezing or symptoms of atopic eczema (Table 4).

Bottom Line:
Age group 31-40 years [0.27(0.09-0.78), p = 0.016] was an independent protective factor for wheezing.Determinants of current rhinitis symptoms were active smoking [2.20 (1.37-3.54), p<0.001], signs of atopic eczema [2.84 (1.48-5.46)] and current wheezing [3.02 (1.70-5.39)].Nationwide surveys are needed to investigate regional variations.

Background: Population-based estimates of asthma and allergic rhinitis in sub-Saharan African adults are lacking. We assessed the prevalence and determinants of asthma and allergic rhinitis in urban adult Cameroonians.

Methods: A community-based survey was conducted from December 2013 to April 2014 among adults aged 19 years and above (N = 2,304, 57.3% women), selected through multilevel stratified random sampling across all districts of Yaounde (Capital city). Internationally validated questionnaires were used to investigate the presence of allergic diseases. Logistic regressions were employed to investigate the determinants of allergic conditions.

Results: Prevalence rates were 2.7% (95% CI: 2.1-3.4) for asthma-ever, 6.9% (5.9-7.9) for lifetime wheezing, 2.9% (92.2-3.6) for current wheezing and 11.4% (10.1-12.7) for self-reported lifetime allergic rhinitis; while 240 (10.4%) participants reported current symptoms of allergic rhinitis, and 125 (5.4%) had allergic rhino-conjunctivitis. The prevalence of current asthma medication use and self-reported asthma attack was 0.8 (0.4-1.2) and 1 (0.6-1.4) respectively. Multivariable adjusted determinants of current wheezing were signs of atopic eczema [2.91 (1.09-7.74)] and signs of allergic rhinitis [3.24 (1.83-5.71)]. Age group 31-40 years [0.27(0.09-0.78), p = 0.016] was an independent protective factor for wheezing. Determinants of current rhinitis symptoms were active smoking [2.20 (1.37-3.54), p<0.001], signs of atopic eczema [2.84 (1.48-5.46)] and current wheezing [3.02 (1.70-5.39)].

Conclusion: Prevalence rates for asthma and allergic rhinitis among adults in this population were at the lower tails of those reported in other regions of the world. Beside the classical interrelation between allergic diseases found in this study, active smoking was an independent determinant of allergic rhinitis symptoms. Nationwide surveys are needed to investigate regional variations.